Method of producing vulcanizable sheet material with multifilament glass cord

ABSTRACT

GLASS CORD COMPOSED OF A PLURALITY OF GATHERED-TOGETHER SUBLEMENTS SUCH AS FILAMENTS, STRANDS, YARNS AND THE LIKE IS COMBINED WITH VULCANIZABLE ELASTOMERIC STOCK MATERIAL IN A DEFINED MANNER AND ACCORDING TO PRESCRIBED METHODS AS TO YIELD A PRODUCT IN THE NATURE OF A CURABLE PREFORM OR BUILDING BLOCK WHICH IS COMBINABLE WITH OTHER SIMILAR BUILDING BLOCKS OR PERFORMS COMPOSED OF GLASS CORD LENGTHS AND ELASTOMERIC STOCK TO YIELD SECOND AND/OR THIRD STAGE BUILDING BLOCKS OR PERFORMS WHICH ARE ULTIMATELY OF UTILITY IN ERECTING, CONSTRUCTION OR BUILDING, BY MOLDING OR OTHER TECHNIQUES, CURED ELASTOMERIC PRODUCTS SUCH AS TIRES, BELTS AND OTHER RUBBER GOODS CONTAINING A GLASS CORD REINFORCEMENT DISPOSED ARRANGED IN A PARTICULARLARY DESIRABLE MANNER AS TO REINFORCEDLY IMPART TO THE ULTIMATE STRUCTURE THE DESIRED AND/OR OPTIMUM CHARACTERISTICS AND/OR PROPERTIES OF THE GLASS CORD AND, OF COURSE, THE INHERENT STRENGTH PROPERTIES OF THE INDIVIDUAL GLASS FILAMENTS MAKING UP THE CORD.

June 26, 1973 A. MARZOCCHI ETAL 3,741,337

METHOD OF PRODUCING VULCANIZABLE SHEET MATERIAL WITH MULTIFILAMENT GLASSCORD Filed May 17, 1971 4 Sheets-Sheet 1 FIG..\

INVENTORS Alrkab nArazoccHl By TQQBEQT RmcAosLAn ATTORUEVS.

June 26; 1973 zoccm ETAL 3,741,837

METHOD OF PRODUCING VULCANIZABLE SHEET MATERIAL WITH MULTIFILAMENT GLASSCORD 4 Sheets-Sheet 2 Filed May 17, 1971 June 26, 1973 MARZOCCH; ETAL3,741,831

METHOD OF PRODUCING VULCANIZABLE SHEET MATERIAL WITH MULTIFILAMENT GLASSCORD Filed May 17, 1971 4 Sheets-Sheet 3 INVENTOR v QLFRED mARzoccHl BYH B ERT R. mcusmfl June 26, 1973 MARzoccHl ETAL 3,741,837

METHOD OF PRO CING VULCANIZ LE SH MATERIAL WIT UL'IIFILAMENT SS C R vFiled May 17, 1971 4 Shoots-Sheet 4 INVENTORS ALFRD mAR'ioccH BY QOBERTR-Nc Pwsmm United States Patent U.S. Cl. 156-171 5 Claims ABSTRACT OFTHE DISCLOSURE Glass cord composed of a plurality of gathered-togethersubelements such as filaments, strands, yarns and the like is combinedwith vulcanizable elastomeric stock material in a defined manner andaccording to prescribed methods as to yield a product in the nature of acurable preform or building block which is combinable with other similarbuilding blocks or preforms composed of glass cord lengths andelastomeric stock to yield second and/or third stage building blocks orpreforms which are ultimately of utility in erecting, constructing orbuilding, by molding or other techniques, cured elastomeric productssuch as tires, belts and other rubber goods containing a glass cordreinforcement disposed or arranged in a particularly desirable manner asto reinforcedly impart to the ultimate structure the desired and/oroptimum characteristics and/or properties of the glass cord and, ofcourse, the inherent strength properties of the individual glassfilaments making up the cord.

The present invention relates to the field of reinforcement ofrubber-like bodies. More particularly, the present invention relates toreinforcement of elastomeric rubber-like bodies with inorganic and, mostpreferably, vitreous reinforcement members such as strands, yarns orcords inclusive of a gathered-together multiplicity of glass filaments.

A wide variety of materials have been used over the years to reinforcerubber in the form of vulcanized products. These vulcanized productsinclude tires, both for over-the-road vehicles and off-theroad vehicles,as well as industrial belts of all kinds including conveyor belts, drivebelts, V-belts, industrial hoses, cushionings and mountings of allkinds. The term rubber as used herein, of course is meant to include notonly natural rubber but the synthetic rubberlike materials includingbutadiene styrene polymers, butyl rubbers, neoprene rubbers, as Well asthe newer synthetic polyisoprene, polybutadiene, ethylene propylenediene materials of the stereo specific type. 'Reinforcement materialsused in these vulcanized rubber products include the natural occurringmaterials such as cotton and, additionally, yarns, strands and cordsformed of such synthetic materials as rayon, nylon, polyester,polypropylene, ethylene copolymers, etc. Steel wire has also beenemployed, most usually in the bead region of tires and, as well, in theformation of belt or breaker strips employed in the radial-type tiresfavored by the European tire manufacturers. The use of glass filamentsas a reinforcement for pneumatic tires has been disclosed in U.S. Pat.No. 2,184,326 assigned to the same assignee as the present application.The mentioned patent discloses broadly the utilization of glass fiberseither as such or in mat form.

It is a principal object of the present invention to provide a system ofreinforcement characterized in that it enables the manufacturer of finalrubber products containing glass reinforcement disposed, located,arranged and composed as to lend the optimum of properties of the glassat the particular region of stress in a manner as may he arrived atpredeterminedly. The reinforcement system of the present inventionprovides a variety of improvements and avoidance of the shortcomings ofthe usually employed tire reinforcements.

The conventional tire reinforcements, of course, are possessed of anumber of shortcomings. Cotton is known to degrade when exposed tomoisture and demonstrates severe elongation. Rayon is possessed of a lowmodulus and, as well, a low strength per unit cross-sectional area. Thepolyamides such as nylon are stronger than rayon but undergoconsiderable elongation and exhibit yield under load. Furthermore, thepolyamides such as nylon, when employed as a tire reinforcement, areusually accompanied by the observance or detection of flat spots in thetire carcass which develop when mounted on an automobile allowed to setin cool weather, resulting in an undesirable thump when the car is putin motion. It is to be additionally noted that conventional textilereinforcement yields tires in which size varies considerably due touncontrollable elongation and yield, resulting in inventory problems.

On the other hand, glass as a candidate reinforcement for rubberpossesses a number of eminently desirable properties when consideredalone. The desirable properties of glass include (a) essentiallyelasticity, (b) essentially no yield under stress, that is, theextensibility does not exceed 3 to 4%, with 100% elastic recovery, (c)excellent dimensional stability and (d) immunity to changes inherent invarying atmospheric conditions. Unfortunately, glass also possessesproperties which differ quite considerably from those of the synthetic,organic materials and accordingly presents realistic problems inconnection with attempting to translate the inherently good propertiesinto practice. It may thus be noted that glass has a stiffness measuredat 322 grams per denier (g.p.d.) whereas nylon has a stiffness rangingfrom 18 to 23 g.p.d.; while polyesters range from 11 to 21 g.p.d. andthe acrylics such as Acrilan and Orlon range from 7 to 10 g.p.d.; whileviscous rayon varies from 11 to 25 g.p.d. Glass also has a very lowbreaking elongation measuring 3 to 4%; whereas the elongation ofpolyester is 19 to 30%, nylon is 16 to 40%, Acrilan is 36 to 40% andviscous rayon is 9 to 30%. Glass also possesses a high specific gravitymeasuring 2.54 compared to 1.14 for the principal polyamide nylon and,as well, the acrylics; 1.5 being the value for rayon and Kodel andDacron measuring from 1.22 to 1.38 and representing two typicalpolyesters. Additionally, toughness on a denier basis reveals acomparison of glass to nylon of 0.75, rayon 0.20, Dacron polyester 0.5and Orlon (an acrylic) 0.4.

It can be seen from the above that glass possesses advantageous as wellas disadvantageous properties, considered from the standpoint of acandidate reinforcement for elastomeric rubber products such as tires,belts, both conveyor and power transmission, etc.

It is a general object of the present invention to provide areinforcement technique calculated to achieve the fullest utilization ofthe advantageous properties of glass, while at the same time overcomingor masking those properties of glass which are less advantageous.

It is a particular object of the present invention to provide areinforcement technique which features a building block approach to thefabrication of elastomeric rubber products, by which is meant atechnique of preparing preforms which may be in the form of planarrectangles, elongate strips of varying thicknesses and widths, elongatesheets of varying lengths, widths and thicknesses and, as well, othershapes of predetermined dimensions containing a precalculable andpredetermined amount of glass disposed in the preform in a preselectedmanner; the preforms or building blocks containing prescribed lengths ofglass in the form of cords, yarns, strands or any of the foregoing ofparticular ply makeup; all of the foregoing being calculated in a manneras permits the preforms to be combined in a desired manner as to yieldthe ultimate vulcanized product containing the glass reinforcement inthe ultimately desired location, selected, of course, upon considerationof the static and dynamic forces and tensions to which the ultimateproduct is likely to be subjected, with the glass located as to bestmeet and/ or accommodate these particular forces, tensions and/orstresses.

It is a significant object of the present invention to provide a methodof producing preforms or building blocks comprising various geometriccross-sectional lengths of vulcanizable elastomeric stock containingglass therein in a preselected form.

It is still another object of the present invention to provide a methodof combining so-called first-stage preforms with like preforms to resultin composite secondstage preforms.

It is a particular object of the present invention to provide amulti-layer sheet material composed of a vulcanizable elastomeric stockcontaining within each layer a plurality of lengths of chopped glasscords; the makeup of the glass in each layer being different in terms ofthe size of the cord, the length of the cord, the angular disposition ofthe cord within the layer as well as other parameter or factor.

It is an object of the present invention to provide a method ofproducing a vulcanizable elastomeric sheet material containing lengthsof glass in the form of cords, strands, yarns, fibers or the like; thecords being arranged in different arrays of orientation within the sheetmaterial.

The foregoing, as well as other objects of the present invention, willbecome apparent to those skilled in the art from the following detaileddisclosure taken in conjunction with the annexed sheets of drawings onwhich there are presented, for purpose of illustration only, severalvaried embodiments of the present invention.

In the drawings:

FIG. 1 is a perspective schematic view illustrating the practice of amethod representing one embodiment of the present invention;

FIG. 2 is a top plan view of a sheet material resulting from thepractice of the method illustrated in FIG. 1;

FIG. 3 is a sectional view taken on the line 33 of FIG. 2;

FIG. 4 is an enlargement of one segment of the sheet material shown inFIG. 3;

FIG. 5 is a plan view schematically illustrating a techniquerepresenting a further embodiment of the present invention;

FIG. 6 is a perspective view schematically illustrating a stock layuptechnique employed in accordance with an embodiment of the presentinvention;

FIG. 7 is a side elevation view illustrating a further molding stepemployed in accordance with one embodiment of the present invention;

FIG. 8 is a perspective view of an array of apparatus componentsoperative to carry out a technique of stock preparation in accordancewith an embodiment of the present invention; and

FIG. 9 is a perspective view similar to FIG. 8, but showing a subsequentprocessing operation constituting a combining of preforms in order toproduce an ultimate sheet material in accordance with a preferredembodiment of the present invention. u

Viewed most basically, the present invention envisions a technique forlocating glass cord reinforcement composed of a plurality of glassfilaments, strands or yarns in a desired preselected manner within theultimately desired vulcanized structure of predetermined physicalconfiguration in order to achieve a maximization of the inherent andmost desirable reinforcement properties of the basic glass element.

Referring now more specifically to the drawings, there is disclosed inFIG. 1 a support table 11 bearing spaced upstanding journal bearings 12and 13 having mounted rotatably thereon a shaft 14, keyed to which is acylindrical drum 15 having outer surface 15a. A shaft 16 situatedparallel to the shaft 14 and drum surface 15a has one end located withinan elongate cylinder 17 suitably supported on flanged support members17a and 17b. The cylinder 17 is suitably controlled by air or fluid in awell-known manner to accomplish axial movement of the shaft 16 to andfro in the direction indicated by the arrows 18. Rotatably mounted onthe end extremity of the shaft 16 is a spool 19 serving as a reservoirfor a continuous length of cord 20 formed of a multiplicity of glassfilaments in the form of strands or yarns combined together in a knownmanner. As a first step in the practice of the present invention, a thinlayer of rubber 21 is releasably wrapped about the outer cylindricalsurface 15a of the drum 15. A continuous length of the glass cord 20drawn from spool 19 is wound about the drum 15 and about the layer ofvulcanizable elastomeric stock carried thereby by the expedient ofrotating the drum while the length of cord is unreeled from the spool 19and wound onto the drum in the manner illustrated in FIG. 1. Repeatedwinds of the glass cord 20 are in closely spaced cont-actingrelationship as controlled by leftward movement of the spool 19 ascarried by shaft 16, controlled in movement in the manner indicated bythe arrows 18 by air or fluid cylinder 17. When the spool 19 is situatedto the left, wherein the length of cord is being wound onto the drumadjacent the leftmost edge 21a of the layer of rubber 21, the cord iscut and the spool 19 moved by operation of the cylinder 17 to therightmost position, ready for a repeated unwinding of a continuous orendless length of cord 20. The drum bearing the layer of rubber and acontinuous wind of glass cord is thence again rotated slowly while thereis applied about the cord and coextensively with the layer 21 a secondlayer 22 (FIG. 3) of rubber. The layer 22 is precut as is the layer 21to a size corresponding generally to the circumferential area of thedrum 15. The sheets 21 and 22 which form the inner and outer layers onthe drum 15 are knitted together by usual means such as a knurledknitting tool and application of a rubber solvent such as methyl ethylketone. Toluene and naphtha can be used in place of methyl ethyl ketone.The laminated or sandwich structure on the drum 15 is then removed byappropriate cutting knife drawn from lateral edge to lateral edge acrossthe drum surface whereupon the structure is removed as a rectangularsheet 23 (FIG. 2) and laid on an appropriate table. Reference to FIG. 2shows the rectangular sheet 23 with a portion of the sheet or layer 22broken away to show the side-by-side winds of cord 20'. FIG. 3 is anedge view of the sheet 23-, while FIG. '4 is an enlargement of a sectionof the edge view.

In FIG. 4, the sheets 21 and 22 are designated as is the spacedside-by-side winds of glass 20. Viewing FIG. 4, it will be appreciatedthat the thickness of the sheet 21 as well as the thickness of the sheet22 may be predeterminedly selected, either being the same thickness or adifferent thickness. Furthermore, the makeup of the cord 20 can, ofcourse, be varied in a predetermined manner, either in terms of thenumber of yarn and subelement strand members or the number of filamentsmaking up the strands and, as well, the twists employed in the plyingand combining of the filaments, strands and yarns in making up the cord.The sheet 23 or similarly composed sheets may be employed as componentsof tires built on conventional tire building equipment or in beltmanufacturing operations such as conveyor belts or the like; it beingappreciated that the dimension, that is, the size in length and width,of the sheet 23 can be varied by appropriate selection of the drum sizeand, of course, appropriate cutting of the initial vulcanizable rubbersheets. The sandwich laminate structures 23 may also be cut in biasfashion, as is well known in the rubber industry, in order that theangular relationship of the essentially mutually parallel cords may bevaried in the incorporation or assembly of the bias cut sheets onto, forexample, tire building drums. The sheets 23 may also be subdivided intobreaker strips or tread reinforcing plies, bias cut in appropriatefashion as will provide the cords in the desired ultimate angulardisposition with respect to the particular reference line, usually theperipheral centerline of the tire. Tread reinforcing plies, e.g., beltplies, produced as described herein embody the advantage of beingunitary multiple-ply structures featuring particular cord angles in eachply, if desired, as will enhance tire performance. These belt plies areparticularly useful stabilizers in the building of radial tires havingcarcass cords radially disposed in the carcass.

In accordance with a further embodiment of the present invention, thesheet 23 (see FIG. 5) is cut into a plurality of strips 23a, 23b, 23c,23d, 23c, 23 23g and 23h. Each of the strips have cords of glassembedded therein, running lengthwise of the strips. The strips, forexample 23g, are then in appropriate manner subdivided into smallersegments, identified by the reference numeral 24a, having anypredeterminedly desired dimensions. The pieces 24a may then be combinedwith each other, for example, in the manner illustrated in FIG. 6-. Thepieces or segments 24a each have a corresponding plurality of lengths ofglass cord 20 embedded therein and shown in dotted outline. The lengthof the cord in a segment 24a will depend upon the distance between thecuts 24b into which the strip 23g is subdivided (see FIG. 5 The layup ofsegments 24w provide a first layer in which the cut edges 24b arelocated in edge-to-edge or abutting contact. An upper layer of segments24a are laid on top of the first layer in edge abutting relationship butwith the edges offset such that one abutting edge, identified forreference purposes as 240, lies midway between the abutting edges 24b ofthe segments making up the lower layer. It will be appreciated that thedimensions of the strips 23a-23h and, as well, the distance between thecuts 24b may be varied to provide segments 24a of a wide variety ofdimensions; the ultimate purpose of which is to provide a multipieceassembly in which there is, in effect, a plurality of lengths of glasscord of predetermined length disposed in a particularly predeterminedlydesired angular relationship with respect to the overall dimension ofthe composite assembly 25 (FIG. 6).

Viewing FIG. 6, it will be appreciated that the rubber sheets, of whichthe pieces 24a are composed, are vulcanizable and are coherent with likepieces when placed in surface abutting contact, as are the lower andupper layers of pieces 24a. A rubber solvent sparingly applied to thesurface will aid in the formation of the composite structure 25. In itssimplest form, the composite structure may be composed of what may bedescribed as a rectangular molding block which may be further describedas a thin multi-component brick or slab. By reason of the inherent tackynature of the unvulcanized rubber, it will be appreciated thatmulti-component bricks or slabs of varying makeup may be produced. Thus,the laminate sheet members 23 may be subdivided into strips such as23a23h of any given width. The strips may, in turn, be subdivided intosegments such as the segments 24a of preselected dimension. Thisusually, in accordance with the present invention, will vary fromone-half inch up to about six inches. Elements 24a of preselecteddimension are then combined somewhat in the manner illustrated in FIG. 6to thereby produce multi-component slabs having any desired length ofglass cord, depending upon the distance between spaced cuts producingthe edges 24b in producing the segments 24a.

FIG. 7 is a schematic side elevation view in the manner of producing avulcanized test specimen which can be tested to determine the effect ofcord length and cord composition on the strength properties of anelastomeric body containing same. FIG. 7 will be described in moredetail in a later example appearing herein. It may be stated here thatreference numeral 30 represents a metal die having in its upper surface31 a depression or female cavity 32 in which is situated a brick or slabmade up of a multiplicity of segments or pieces 24a. The multi-componentslab is located in the cavity 32 whereupon top plate 33 is lowered,effecting closure of the cavity 32, whereupon the whole unit is heatedby suitable means, effecting cure of the assembled array of segments24a. The cured end product then serves as a blank from which may be diecut a dumbbell specimen for tensile testing in a manner described in thelater example.

Reference may now be had to FIGS. 8 and 9 wherein is disclosed an arrayof apparatus elements designed in concert to produce, in accordance withthe present invention, a sheet material or building block containinglengths of glass cord of predetermined length and angular dispositionfrom a supply of continuous lengths of glass cord and a supply ofappropriate rubber stock.

Referring first to FIG. 8, there is shown at the lefthand extremity anarray of spools 50, each containing a supply of glass cord comprising,as described hereinbefore, an assembled plurality of glass strands oryarns, in turn made up of a multiplicity of glass filaments. The cordsare preferably impregnated, in a manner to be described, for readyassimilation into the rubber stock or they may alternatively besubjected to an impregnation upon withdrawal from the supply spools 50,albeit not particularly disclosed herein. The cords in spaced, parallelarray are identified by the reference numeral 51. The cords are drawnfrom the supply spools 50 by a pair of counter-rotating rollers 52 and54. The rollers 52 and 54 rotate in the direction indicated by thearrows and each bear on their respective surfaces a layer of rubber. Thelayers of rubber and the parallel array of cords converge at the nip orline of convergence of the rubber carried by the spaced rollers; the nipbeing identified by the reference numeral 53. The rollers or drums 52and 54 are rotatably mounted on suitable shafts 52a and 54a. The layerof rubber carried on the surface of roller 52 is provided by feeding asupply of appropriate elastomeric stock 55 into the nip region betweenroller 52 and cooperating roller 56 which rotates in an oppositedirection to roller 52 and is spaced slightly therefrom a distance whichcan be controlled by adjustment of shaft 57 upon which drum 56 ismounted for rotation. The elastomeric stock 55 is worked in passingbetween rollers 52 and 56 and is spread out evenly across the surface ina manner well understood. Similarly, a supply of stock 60 is fed betweenlower roller 54 and a cooperating roller 62 in parallel relationshiptherewith and mounted to define an appropriate predetermined distancebetween the surfaces as controlled by disposition of the adjustableshaft 63 which is rotatable and upon which roller '62 is mounted. Therollers 54 and 62 cooperate to convert the feed stock 60 into a thinlayer carried on the surface of roller 54 which convergingly meets thelike layer on roller 52 carrying therewith the parallel strands or yarns51, shown in dotted outline, downstream from the rollers 52 and 54.Tension in the spaced yarns or cords 51 is, in part, maintained by thecounter-rotating rollers 65 and 66 which are mounted downstream incounter-rotating, horizontally disposed, vertically spaced relationship,as shown, and between which passes the rubber sheet material 67 formedby the convergence of the layers of rubber converging in the nip region53. The space between rollers 65 and 66 is adjustable to finally gaugethe thickness of the sheet material 67 and, as indicated, to maintaintension in the sheet material 67 and specifically the cords 51. Furtherdownstream, the sheet material 67 passes between another pair ofcooperating vertically spaced drum rollers 68 and 69 which, in array,are situated slightly below the horizontal plane of the sheet material67. The purpose for this relationship is to provide for positive cuttingengagement as between the sheet material and a plurality of upstanding,horizontally spaced cutting knives 71 projecting upwardly from knifesupport bar 52. Driven parallel spaced conveyor belts 73 located betweenthe knives serve to support the rubber sheet material as it is slicedinto strips 74 by the array of upstanding knives disposed in transversearray with respect to the downstream moving sheet material.

The array of rollers 52, 56, 54 and 62 is, for ease of illustration andunderstanding, shown schematically, albeit that commercially availablecalendering equipment is usable in actual production.

The strips 74, upon emergence from guide rollers 68 and 69, pass in asomewhat downwardly inclined direction between a pair ofcounter-rotating drum rollers 76 and 77 mounted on suitable drivenshafts. The path of the strips is determined and aided by a conveyorbelt arrangement, previously identified by the reference numeral 73,comprising a plurality of side-by-side belts which proceed continuouslyover roller 66, bar element 72, drum roller 69, drum 77, reverselyaround roller 78 and thence under drum 77, over idler roller 79, thenceunder drum roller 69 and finally upwardly reversely to the point oforigin about drum roller 66. The drum 76 has, extending radially fromits surface, a plurality of parallel spaced cutter blades 76a whichpress against roller 77 and thus cut the strip passing between rollers76 and 77. The spacing of the cutter blades 76a, which are disposedparallel to the axis of rotation, is selected to correspond to thedimension or length into which it is desired to cut the strips 74. Whenthe strips have been cut into segments 80 by cut 801:, they proceed, asshown, onto a conveyor 81 composed principally of an endless conveyorbelt 82 which proceeds about an array of rollers in conventionalfashion. Situated above the conveyor belt are a pair of overhanginghorizontal support bars 83 upon which vertically depend a plurality ofrelatively flexible fingers 84 which serve to insure alignment of theplurality of generally rectangular segments 80 in the direction oftravel. The spacing of the cutter blades 76a is desirably selected suchthat the dimension of the segments along the path of travel is somewhatlonger than the width dimension of the strips 74. The speed of theconveyor system 81, principally the conveyor belt 82, is controlledslightly faster than the belts 73 so that the slabs 86 assume a somewhatspaced and spread out relationship as shown in the left-hand segment ofFIG. 9. Reference numeral 90 identifies the delivery end of a conveyorarrangement like the conveyor arrangement 81. As can be seen, theconveyor 90 proceeds at somewhat of an angle to the axis of theprincipal conveyor arrangement 81 and is shown delivering a plurality ofsegments or pieces 92 in angular overlapping relationship with thesegments 80. It will be appreciated that the segments 92 are the productof the operation of an array of apparatus elements as illustrated inFIG. 8. The slabs or pieces 92 and the pieces 80 which underlie thepieces 92 and are angularly disposed thereto proceed in the mannerillustrated to approximately the position identified by the referencenumeral 95. At this point, there is situated another conveyor discharge97 angularly disposed to the conveyor arrangement 81 and generallyopposite to the angular relationship of the conveyor arrangement 90.Pieces or segments 98 carried on the conveyor arrangement 97 are theproduct of the operation of an array of apparatus elements upon a supplyof glass cord and stock rubber as above described in connection withFIG. 8. The slabs 98 pass from the conveyor arrangement 97 intooverlapping or overlying and angular relationship with the segments orpieces 92 and the segments or pieces 80. The overlapping array ofangularly disposed segments proceed on the conveyor downstream, passingbetween a pair of counter-rotating rollers 100 and 101 mounted forrotation on suitably driven shafts which are spaced a preselecteddistance in order to compress the array of segments, pieces or slabstogether into a relatively unitary sheet identified by the referencenumeral 103. As to the sheet 103, the reference numerals a, 92a and 98arespectively identify the axes of the rectangular segments or piecesproceeding from the conveyor arrangements 81, and 97.

It will be appreciated, by reason of the above, that the sheet 103 thuscontains embedded therein mutually parallel cords of glass generallydisposed axially with respect to the individual segments or pieces 80,92 and 98; the angular relationship of the cords in the pieces 80, 92and 98 being determined by the angular relationship of the conveyorsystems, particularly the conveyor systems 90 and 97 with respect to theconveyor system 81.

It will further be appreciated that the relative angular relationship ofthe longitudinal axis of the segments, and correspondingly the angularrelationship of the cords embedded therein, may be controlled by theemployment of members 83 with depending fingers 84. The ultimateobjective, of course, is to provide a sheet material composedprincipally of a vulcanizable elastomeric matrix having embedded thereincords of glass, the length of which can be predeterminedly controlled,and the cords also being predeterminedly arranged at different angularrelationships with respect to the longitudinal axis of the principalsheet 103. The sheet 103 can be bias cut or subdivided into any sizesheets as desired, being used thereafter, of course, as a former orbuilding block in the layup of multiple pieces and formers formed ofvulcanizable elastomeric stock rubber and thereafter vulcanized or curedin a desired mold or other method of vulcanization to achieve a moldedcured product, such as a tire, a conveyor belt, a V-belt, a shockabsorber or any one of a variety of mechanical rubber products. Theultimate product, of course, will be characterized in that it containsglass reinforcement which is located in a desirable location as opposedto indiscriminate location. The length of the glass can bepredeterminedly controlled as can the angular relationship of the glasscords in order, of course, as indicated hereinabove, that the glass maycontribute to the finally configurated part the maximum in terms of thereinforcement capabilities of the basic glass filament or the compositeglass strand, yarn or cord.

It has been determined in accordance with the present invention that thequantity of glass, the location of the glass, the angular disposition ofthe glass cords, in terms of aggregate array, and the length of theglass cord, all have an effect on the physical properties exhibited bythe ultimately vulcanized molded piece. A significant utility for thecomposite sheet material 103 is in fabricating unvulcanized or greentread reinforcing ply or breaker strip structures. Thus, it will beunderstood that the sheet material 103 may be subdivided into a striphaving a length corresponding to the circumference of the ultimate tireand a width corresponding to approximately the tread region of theultimate tire. The strip may be Wrapped about the previously appliedcarcass elements and just prior to the application of the camelback ortread stock, providing, in elfect, a multiple layer, tread reinforcingply in a single step. Thus, viewed in section, the sheet material as cutinto the vulcanizable belt plies will be seen to be composed of a lowerlayer, a middle layer and an upper layer, each different from the otherin terms of the angular relationship of the mutually parallel glasscords in each of the layers. It will be appreciated that the length ofthe cord in each of the layers can be varied, depending upon theappropriate operation of the technique and apparatus illustrated inFIGS. 8 and 9.

The glass filaments of which the cords 51 are composed are manufacturedand marketed commercially. The fibers are drawn from a molten supply ofglass contained in a platinum container having a large plurality of veryfine holes in the bottom thereof from which the molten glass is drawn athigh rates of speed which attenuate the glass into extremely finediameter. The glass filaments are pretreated as drawn from the platinumcontainer, usually called a bushing, with a size serving to enhance thecompatibility of the ultimate glass yarn with the elastomeric matrix forwhich it is best. A suitable size is composed of 0.5-2.0 percent byweight of gammaaminopropyltriethoxy silane, 0.3-0.6 percent by weight ofa lubricant and the remainder water. Other amino silanes may be employedas a size material. The drawn filaments, as indicated earlier herein,are combined with like filaments to form a strand. The number offilaments to form a strand may vary from several hundred upwards to acouple thousand. The filaments may be twisted or left in untwistedrelationship in forming the strand. Thereafter, a plurality of strandsare combined with or without twist to form a yarn. In like fashion, amultiplicity of yarns may be combined, with or without twist, to form anultimate cord such as the cord 51 (FIG. 8). At some stage of theformation of the cord or even after the formation of the cord, the glasselement assembly is desirably impregnated with an elastomeric baseimpregnant in order to improve further the compatibility of the cord ofglass subelements into the ultimate elastomeric product. The impregnantmay be an appropriate elastomeric material dissolved in a suitablesolvent for that particular compound to form a somewhat viscous liquidwhich can be coated onto or impressed into the interstices of the cordby suitable immersion and/or immersion coupled with distortion of thecord and subelements to improve impregnation. A suitable impregnant islisted in Table 1 below.

TABLE 1 Parts by weight Neoprene rubber 100 Powdered magnesium oxide 4Powdered zinc oxide 5 Channel black Thiate B (trialkyl thioureaaccelerator) 1 The above ingredients are suitably mixed on aconventional rubber mill combined with a suitable or appropriate rubbersolvent in amounts as will form a liquid impregnant bath of convenientviscosity. An equally suitable impregnant is composed of about 60 partsby weight of 38 percent dispersed solids inclusive of abutadienestyrene-vinyl pyridine terpolymer latex, a buta-diene styrenelatex and a resorcinol-formaldehyde resin in combination with about 40parts by weight of water. The 38 percent dispersed solids system ismarketed under the trade name Lotol 5440 by Uniroyal, formerly U.S.Rubber Company.

To illustrate the effect of glass cord disposition, makeup and length ofcord, a number of cured test slabs were prepared generally in the mannerillustrated in FIGS. 1-6.

EXAMPLE I A layer of stock was applied to a drum, such as the drum 2 1as shown in FIG. 1. Following this, a continuous cord composed of threestrands of 204 glass filaments each was, in the manner illustrated inFIG. 1, laid down around the layer of rubber at a spacing of about 16ends per inch. A top layer of rubber was applied and stitched down. Theultimate laminate measured 0.048 inch in thickness, with each layer ofrubber stock measuring 0.020 inch. The laminate as a sheet, generally asillustrated in FIG. 2, was removed from the drum and cut up into stripsin the manner of FIG. 5 and thereafter the strips subdivided, also asshown in FIG. 5, whereupon an assembly in the manner of FIG. 6 wasconstructed. The cutting into strips and into lengths was carried out inthe manner described in connection with pieces 24a of FIGS. 6 and 7. Thelayup of the pieces was carried out as shown in FIG. 6; the cord lengths20 measuring one inch. The plurality of laid up pieces was molded into aslab as shown in FIG. 7 and thereafter the slab was cut into dumbbellspecimens with the cord length longitudinally thereof. Similar slabswere prepared but made up of different sized pieces, specifically as toglass cord length. The molded slabs contained approximately 15 percentby weight fiber glass based on the total Weight of cord and rubber. Thedumbbell specimens were subjected to conventional testing employed inthe rubber industry and the results of the test are contained in Table 2below.

TABLE 2 Modulus Elonggation 20% 40% 60% Tear No'rE.Fiber glasscontent=15%; Rubber stock The foregoing table demonstrates the effect ofcord length on tensile strength, elongation and modulus, as well as tearstrength. In the above test, the tensile pull, of course, is inalignment with the axis of the dumbbell specimen and, of course, withthe axis of the cords embedded therein.

In accordance with a further embodiment of the present invention, it isenvisioned and proposed that building block members in the form ofvulcanizable elastomeric stock containing glass cords embedded thereinmay be prepared in a manner as will yield the slab in the form of asheet-material of some thickness and in which the glass elements in theform of yarns, strands or cords are oriented vertically; that is, normalto the planar surfaces of the sheet material. This can be accomplishedby starting with a sheet material in which the yarns, strands or cordsare oriented horizontally and perhaps even longitudinally of the sheetmaterial. The sheet material is passed between a pair of calendar rolls,in which one roll is controlled to rotateat a much higher rate of speedthan the other, whereupon the cords are displaced due to the distortionof the rubber in passing between the spaced counter-rotating rolls in amanner that on the downstream side of the rollers the cords, strands oryarns would have been displaced into a vertical relationship with thefacing surfaces of the slab or sheet material.

While we have disclosed in considerable detail the manner of carryingout our invention, both in terms of formulation and process steps, itwill be appreciated that variations and substitutions may be madewithout, in fact, departing from the inventive concept. Accordingly, allsuch modifications, variations and substitutions in material areintended to be included within the scope of the invention.

What is claimed is:

1. The method of producing a vulcanizable preform for use in themanufacture of vulcanized rubber products, said method comprising:

wrapping a first layer of vulcanizable elastomer about a rotatable drumof cylindrical configuration, rotating said cylindrical drum on itslongitudinal axis, feeding a continuous length of multi-filament glasscord onto said rotating drum and about said layer in repeatedside-by-side winds which are generally transverse to said longitudinalaxis,

wrapping a second layer of vulcanizable elastomer sheet material aboutsaid first layer and coextensively therewith to form a compositelaminate material containing the winds of glass cord sandwiched betweensaid first and second layers,

1 1 cutting said composite material from marginal edge to marginal edgegenerally parallel with the longitudinal axis, forming thereby amultilayered sheet, and subdividing said sheet into smaller pieces ofpreselected dimension adapted for incorporation into a desired product.

2. The method as claimed in claim 1, wherein said smaller pieces arecombined with like pieces to form a sheet material containing thelengths of glass cord in a preselected pattern.

3. The method as claimed in claim 1 which includes the step of:

combining said pieces of preselected dimension to form a sheet materialcontaining said lengths of glass cord in a preselected pattern featuringangular disposition of said cord lengths. 4. The method of producing avulcanizable preform containing reinforcing lengths of glass cord, saidpreform being of utility in the manufacture of rubber products, saidmethod comprising:

continuously forming a sheet of vulcanizable rubberlike stock havingembedded therein a plurality of continuous lengths of glass cord inessentially mutually parallel relationship lengthwise of said sheet,

cutting said sheet longitudinally into a plurality of strips,

cutting said strips generally transversely to form a plurality ofsmaller pieces, positioning a plurality of said pieces in conjointcoplanar array so that the cords are arranged in a substantially uniformpattern of orientation,

combining said pattern of pieces with a separately prepared pattern ofpieces featuring a different cord orientation to thereby form atwo-layer aggregate and 12 uniting the two layers into an integralcontinuous sheet. 5. The method of producing a continuous multi-layersheet of vulcanizable elastomeric material containing glassreinforcement, said method comprising:

directing a beam array of glass strands, yarns, cords or the likebetween a pair of convergingly moving sheets of vulcanizable elastomericmaterial,

compressing the formed composite sandwich structure as it proceedslongitudinally,

cutting said longitudinally proceeding sandwich structure into aplurality of longitudinal strips,

cutting said strips transversely to form a plurality of slabs,

arranging said plurality of slabs in a preselected pattern oforientation on a continuously moving conveyor,

superimposing on said arrangement of slabs of the preceding step asecond plurality of similar slabs having a preselected pattern oforientation,

compressing said superimposed arrangements of slabs into a unitarycomposite sheet material and collecting said sheet material.

References Cited UNITED STATES PATENTS 1,355,525 10/1920 Baker 156-1711,046,211 12/1912 Milton 156-171 NORMAN G. TORCHIN, Primary Examiner IL. GOODROW, Assistant Examiner US. Cl. X.R. 156-l74

